Mercury switch relay



Dec. 15, 1936. c. H. LARSON 2,064,478

MERCURY SWITCH RELAY Filed Aug. 24, 1955 3 Sheets-Sheet 1 Filed Aug. 24, 1955 3 Sheets-Sheet 2 wimmmmmmmmmm mmmh ummwwmwmmm lllllllllll Dec. 15, 1936. c. H. LARSON 2,064,478

MERCURY SWI TCH RELAY Filed Aug. 24. 1935 3 Sheets-Sheet 3 Patented Dec. 15, 1936 UNITED STATES MERCURY SWITCH RELAY Carl H. Larson, Elkhart, Ind., assignor to The Adlake Company, a corporation of Illinois Application August 24, 1935, Serial N0. 37,724

9 Claims.

In my Patent No. 1,967,946 I disclose a mercury tube relay of the plunger type equipped with an adjusting device for selectively positioning the mercury tube with respect to the magnetic circuit in order to obtain certain time relay characteristics. The adjusting means disclosed therein consists of a cap surmounting the tube and having a threaded stem projecting upwardly through an opening in a fixed support to receive a nut for effecting a slow motion adjustment of the switch tube. A spring is interposed between the support and the cap for steadying the switch within the coil.

The present invention is an improvement on the construction shown in the above identified patent, and some of the objects and advantages of the improved relay are as follows: The adjusting device is a part of the relay unit and may be set at the factory; the adjusting nut is placed in a position where it is readily accessible for-making adjustments; the tube is supported by the adjusting device in a manner that permits accurate adjustments to be made and retained even though the relay unit is jarred in service; the lowerportion of the tube is provided with a base which not only protects the tube from damage and minimizes the possibility of short-circuiting,

but also furnishes a convenient place for grip-' ping the switch and holding it in its proper position within the magnetic circuit; and, finally, the relay parts may be made and assembled with minimum cost and labor.

The adjusting device of this invention is applicable, not only to time delay relays, but also to quickacting relays, the adjustments being made for the purpose of obtaining given operating characteristics such as selected pick-up and drop away values.

Further and other objects and advantages will become apparent as the disclosure proceeds and the description is read in conjunction with the accompanying drawings, in which- Fig. 1 is a vertical, sectional view through a mercury switch relay embodying the principles of this invention, the section being taken on the line i-l of Fig. 3;

Fig. 2 is' a front elevational view of the relay shown in Fig. 1;

Fig. 3 is a plan view of the same;

Fig. 4 is a view showing a modified form of the invention, the switch tube in this case being mounted within the relay coil;

Fig. 5 shows the energized position of the switch tube shown in Fig. 4;

Fig. 6 is a detached perspective view of the adjusting rod and switch holder;

Fig. 7 is a perspective view of the magnetic circuit associated with the switch tube, and the 5 bracket which supports the adjusting rod;

Fig. 8 is a plan view of the assembled relay shown in Fig. 4;

Fig. 9 shows another modified form of the invention in which the switch tube is mounted ex- 10 supports the switch tube from the adjusting arm;

Fig. 13 shows a modified form of clip; Fig. 14 is a perspective view showing the brackets which support the relay and hold the adjusting rod; and

Fig. 15 is a perspective view 01' the laminated core showing the pole clips slightly spaced from the core for clarity of illustration.

But this specific illustration and the corre-' sponding specific description are for the purpose of disclosure only and are not to be construed as 26 imposing limitations on the claims except as may be required by the prior art.

In the form of the invention shown in Figs. 1-3 inclusive, the relay comprises a cast aluminum base 20 having an upstanding wall 2i which is provided with reinforced apertures 22 for receiving horizontal cores 23 of metal having low reluctance, such as Svea-electrical iron or Permalloy. The cores 23 have reduced diameters where they pass through the apertures, as indicated at 2|, and they are supported in place by threaded bushings 25 and lock nuts 26.

Relay coils 21 are mounted on the cores (there are four cores and four relay coils in this embodiment of the invention) and their bakelite spools 28 are spaced from the lock nuts 26 by cork or felt washers 29.

The rear ends of the cores 23 are reduced in diameter and threaded to receive links 30 of magnetic material which are held in place by nuts 3 I. Each pair of cores with the link that connects the component cores forms a magnetic circuit thatis closed except for the air gap between the forward ends of the cores.

The reduced ends 2| 0! the cores are carefully 60 machined to proper diameter and are then driven into suitable apertures in pole pieces 32 and 33, each consisting of a bar of low reluctance material (Svea-electrical iron, Permalloy, or similar material) and having three sets of vertically alined apertures for receiving mercury switches 34, 35 and 38. These switches are of the type fully disclosed in my copending application, Ser. No. 759,634, filed December 29, 1934, and reference is made to that application for a full disclosure of the details of the switches and the electrical circuit associated therewith.

It is important that the mercury tubes 34, 35 and 38 be properly positioned with respect to the magnetic air gaps which operate them if the relay is to function as intended.

In the present invention, this is accomplished by supporting the tubes within the pole pieces 32 and 33 by adjusting devices, generally designated 48, one being associated with each mercury tube. After the pole pieces 32 and 33 have been mounted on the cores 23, vertical holes are drilled through the pole pieces and cores to receive adjusting rods 4|, the lower ends of which are equipped with spring clips 42 of music wire bent into the form best shown in Fig. 3 and secured to the adjusting rods by nuts 43 and 44. A spring 48 interposed between a wear washer 48 and the nut 43 tends to. force the rod downwardly and this is resisted by nuts 41 and 48 which are screwed on the threaded end 48 of the adjusting rod. Cork washers 58 are provided between the lower nut 41 and the pole piece 32.

The laterally projecting portion of the clip 42 engages a base 51 of insulating material which comprises a sleeve of Bakelite slipped over the lower end of the mercury tube and held in place by a sealing compound generally indicated at 82. The base not only serves to protect the lower end of the mercury tube from breakage due to accidental blows, but also lessens the chance of having the tube short circuited by blows which force the bared ends of the electrodes together.

Since the relay disclosed in Figs. 1-3 employs three mercury tubes, it is impractical to obtain a symmetrical arrangement of the three adjusting devices. Accordingly the adjusting devices for the tubes 34 and 88 are placed adjacent one another, the former being to the rear of the pole pieces and the latter being nearer the front of the pole pieces.

Supporting the tube at the bottom not only gives a more stable support for the switch but also saves considerable space. The adjusting device being a part of the relay unit, the tubes may be accurately positioned at the factory and the manufacturer has assurance that when the relay is set up for service, it will operate as intended. However, if any adjustment is necessary when the relay is installed, it may be conveniently accomplished.

In the form of the invention shown in Figs. 4-8 inclusive, the mercury tube, generally designated 88, is mounted within a relay coil 8| and has an external iron circuit which consists of a laminated U-shaped yoke 82 of high grade transformer iron, pole pieces 83 and 84, and pole clips 88 and 88, the pole clips being secured to the yoke 82 by screws 81 and nuts 88. A brass ring 88 spaces the pole sleeves 83 and 84 a predeter-. mined distance.

The mercury tube fits loosely within the pole sleeves 83 and 84 and brass ring 88 and is adapted to be adjustably positioned with respect to the air gap between the pole pieces by an adjusting device, generally designated 18, which consists of an adjusting rod 1|, mounted in a guide 12 riveted to a bracket 13 attached to the yoke 82 by screws 14 and nuts 18 and having openings 18 in its rear face for attachment to some fixed support. The rod 1| has at its lower end a laterally extending arm 11 which is drilled to receive a tube holder 18 consisting of music wire bent to the form best shown in Fig. 6. A spring 18 is interposed between the lower lug 88 of the guide 12 and the arm 11 for yieldably urging the rod downwardly, and nuts 8| and 82 are screwed on the threaded end 83 of the adjusting rod for resisting the downward thrust. Cork or felt washers 84 are telescoped over the adjusting rod 1| between the lower nut 8| and the top lug 85 of the guide 12.

The tube 88 is provided with a base 88 consisting of a bakelite sleeve held in place by a sealing compound, as indicated at 81, and the ring portion 88 of the tube holder 18 engages a groove in the tube base for supporting the tube within the magnetic circuit. It is obvious that by suitably manipulating the nuts 81 and 82, the tube 88 may be raised and lowered within the coil 8i, thus changing the characteristics of the relay. particularly as to the pickup and drop away values.

In my Patent No. 1,967,846, I was particularly interested in using the adjusting device for changing the time characteristics of a time delay mercury switch; in the present case, the adjusting device is used primarily for controlling the amount or power required for operating the relay.

The mercury tube switch 88 comprises, briefly, a switch envelope 88 through the base of which electrodes 88, 8i and 82 are sealed, the two latter electrodes being enclosed within insulating sleeves :83 for a portion of their lengths. A quantity of mercury 84 is in the switch envelope and its position within the envelope is adapted to be changed by a displacer, generally designated 88 consisting of a glass tube 88 closed at its top and an iron sleeve 81 telescoped over the tube 88 and held in place by a spring 88 which is tightly fitted over the top of the tube 88 and has its lower coils close together for engaging inwardly turned lugs 88 of the sleeve 81.

When the displacer is in its lowermost position, as shown in Fig. 4, the bottom of the tube 88 rests upon a spring I88 anchored on the central electrode 88 and in this position of the displacer, mercury bridges the electrodes 88 and 82 but the entrapped gas within the tube 88 holds the mercury away from the electrode 8 I.

When the coil 8| is energized, the displacer rises to the position shown in Fig. 5 and before the mercury level reaches the bared end of the electrode 81, the outside mercury level has dropped sufllciently to uncover the bared end of the electrode 82, thus preventing more than one of the insulated electrodes 8i and 82 from being in electrical circuit with the electrode 88 at any given time.

The adjusting device for the relay disclosed in Figs. 9-15 inclusive is used where the mercury tube here designated H8 is mounted exteriorly of the relay coil. In this case, the core is made up of two separable parts iii and 2, as described in patent to Hedin 1,967,948, issued July 24, 1934. The two halves of the core are held together by a mounting bracket H3 and by a second bracket I 14 which carries a guide member I 18 for the adjusting rod I 18. As before, the pole clips H1 and H8 receive the tube rather loosely so that the adjusting device may position the tube within the magnetic circuit.

In place of using a wire clip, such as shown in Fig. 12, it is possible to use a band clip H8 as shown in Fig. 13, the ends of the band having lugs I28 which may be forced together by a screw IZI. The switch base I22 is suitably grooved to receive the band.

The mercury tube 1 I0 differs from the tube 60 only in details which are unimportant here, and for that reason further description is deemed unnecessary.

It will be noted that the lower pole piece H8 is cut away, asindicated at I23 so that the condition of the electrodes and mercury level may be watched while the switch adjustment is being effected.

The bracket H3 holds the two halves Ill and H2 of the core firmly together and thereby minimizes the reluctance of the iron circuit.

It will be noted that new switches may be substituted for old ones, in any *of the relays disclosed, with minimum eifort and loss of time.

What I claim is:

1. In combination, a vertical switch envelope, spaced electrodes in the envelope, a mercury fill, a magnetically responsive displacer for shifting the mercury level to change the condition of the circuit through the electrodes, a magnetic circuit associated with the displacer including a metal yoke of low reluctance substantially closed except for an air gap adjacent to the displacer, and means carried by the magnetic circuit for adjustably supporting the switch envelope in selected relation with the magnetic circuit, said means including a rod and a slow motion device.

2. In combination, a vertical switch envelope, spaced electrodes in the envelope, a mercury fill, a magnetically responsive displacer for shifting the mercury level to change the condition of the circuit through the electrodes, a magnetic circuit associated with the displacer including a metal yoke of low reluctance substantially closed except for an air gap adjacent to the displacer, a sleeve of insulating material rigidly mounted on the bottom portion of the switch envelope, and means carried by themagnetic circuit for engaging the sleeve to hold the switch envelope in its desired relation with the magnetic circuit.

3. In combination, a vertical switchenvelope, spaced electrodes in the envelope, a mercury fill, a magnetically responsive displacer for shifting the mercury level to change the condition of the circuit through the electrodes, a magnetic circuit associated with the displacer including a metal yoke of low reluctance substantially closed except for an air gap adjacent to the displacer, and slow motion means carried by the yoke. for adjustably supporting the switch envelope in its proper relation to the yoke, said means including a threaded rod substantially parallel to the switch envelope.

4. In combination, a vertical switch envelope, spaced electrodes in the envelope, a mercury fill, a magnetically responsive displacer for shifting a the mercury level to change the condition of the circuit through the electrodes, a magnetic circuit associated with the displacer including a metal yoke of low reluctance substantially closed except for an air gap adjacent to the displacer, slow motion means carried by the yoke for adjustably supporting the switch envelope in its proper relation to the yoke, said means including a threaded rod substantially parallel to the switch envelope, and an arm on the lower end of the rod for engaging the switch envelope.

5. In combination, a fixed support, a magnetic circuit attached to said support and including a metal yoke of low reluctance substantially closed except for a single air gap, a mercury switch of the type including a magnetic armature mounted in operative relation with the magnetic circuit, and means for adjustably supporting the switch in selected relation to the magnetic circuit, said means including a sleeve of insulating material rigidly mounted on the bottom portion of the switch envelope and a slow motion device engaging the sleeve.

6. In combination, a fixed support, a magnetic circuit attached to said support and including a metal yoke of low reluctance substantially closed except for a single air gap, a mercury switch of the type including a magnetic armature mounted inoperative relation with the magnetic circuit, and means carried by the magnetic circuit for adjustably supporting the switch in selected relation to the magnetic circuit, said means including a slow motion device rigidly attached to the lower portion of the switch.

7. In combination, a fixed support, a magnetic circuit attached to said support and including a metal yoke of low reluctance substantially closed except for a single air gap, a mercury switch of the type including a magnetic armature mounted in operative relation with the magnetic circuit. and means for adjustably supporting the switch in selected relation to the magnetic circuit, said means including a sleeve secured to the lower portion of the switch, and a vertically adjustable arm engaging the sleeve.

8. In a mercury switch relay of the class described, a relay coil, an iron circuit substantially closed except for a single air gap, a. mercury switch associated with the iron circuit and comprising a mercury switch envelope, a quantity of mercury in the envelope, electrodes sealed through the base of the envelope and having portions propecting outside thereof, a displacer responsive to the coil for shifting the mercury level to change the condition of the electrical circuit through the electrodes, a sleeve of insulating material telescoped over the lower end of the envelope and projecting beyond the base thereof, and a sealing compound in the projecting end of the sleeve.

9. In a mercury switch relay of the class described, a relay coil, an iron circuit substantially closed except for a single air gap, a mercury switch associated with the iron circuit and comprising a mercury switch envelope, a quantity of mercury in the envelope, electrodes sealed through the base of the envelope and having portions projecting outside thereof, a displacer responsive to the coil for shifting the mercury level to change the condition of the electrical circuit through the electrodes, a sleeve of insulating material telescoped over the lower end of the envelope and projecting beyond the base. thereof, and a sealing compound in the projecting endof the sleeve, and means for supporting the switch in selected relation to the iron circuit, said means including a vertically adjustable arm engaging the sleeve.

CARL H. LARSON. 

